Carbomer is a white powdery substance, easy to absorb moisture and agglomerate, soluble in water, ethanol, alcohol and glycerin. Its 1% aqueous solution has a pH of 3.0 and can be neutralized with alkali. The hydrogel formed by carbomer is the most viscous when the pH is 6-12. When the pH is <3 and >12, the viscosity decreases. The presence of strong electrolytes will also reduce the viscosity. When exposed to sunlight, it will quickly lose its viscosity. The addition of antioxidants can slow down the reaction.
Many manufacturers will encounter various problems when using carbomer, because carbomer is extremely hydrophilic, and the dry powder of carbomer (carbomer) is very hygroscopic, just like other hygroscopic powders. When improperly put it into water or other polar solvents, it is easy to form agglomeration or incomplete wetting. Other powders will eventually reduce and dissolve after agglomeration, but carbomer will not dissolve easily after agglomeration, because once the outer layer of the agglomerate is completely infiltrated, moisture will not easily penetrate into the inner dry part, and finally appears Massive phenomenon.
Carbomer dissolved in water
A few days ago, several customers asked us how to avoid the phenomenon of carbomer formation. Here are several methods for reference.
1. Sprinkle carbomer on the water (note: it is carbomer on the water, not carbomer with water), let it stand for one night to fully dissolve;
2. Grind the carbomer and glycerin (or propylene glycol, depending on the prescription) in the mortar evenly, then add water to grind evenly;
3. Add a certain amount of water to the agitator, slowly add carbomer under rapid agitation, and continue to agitate for 1-2 hours after the addition is completed, so that it fully dissolves and swells;
Here are some additional points:
1. If it is a small test in the laboratory, it is recommended to use the method 2 or 3;
2. If it is a pilot test or production, the methods 1 and 3 are more suitable. The method 1 may have jelly-like clumps, but the problem is not big: after the colloid mill, you can get a very uniform colloid. After the colloid mill, there may be more air bubbles, which can be defoamed by vacuuming and placing it overnight.
3. The above method only obtains carbomer colloid. To obtain the gel matrix, the pH must be adjusted to 6-10 with triethanolamine or sodium hydroxide solution. The resin particles must be evenly dispersed in cold water. Carbomer can be sieved into agitated vortex with high-speed stirring at 500-800rpm. Optional dispersing equipment can be ejector, flocculation disperser, and conventional disperser. A
The above method is purely personal experience. Each company uses different carbomer manufacturing equipment, and the method also varies from person to person. If you have a better way to avoid carbomer formation, please leave a message for advice, carbomer has For many different models, Desheng currently sells the Carbomer 980 and Carbomer 940 relatively well. After the equipment has been upgraded, it has reached a very good mass production.
